ci(build-kernel): simplify kernel build action and set SKIP_DEFCONFIG

Remove the conditional logic that modified the GKI fragment to disable CONFIG_TRIM_UNUSED_KSYMS. The build command now unconditionally sets SKIP_DEFCONFIG=1 when using build.sh, streamlining the workflow and relying on the fragment as provided.

.github/actions/build-kernel/action.yml

@@ -8,16 +8,9 @@ runs:
       working-directory: ${{ github.workspace }}/kernel
       run: |
         set -euo pipefail
-
-        if [ -f "$GITHUB_WORKSPACE/wild_gki.fragment" ]; then
-          sed -i '/^CONFIG_TRIM_UNUSED_KSYMS=/d' "$GITHUB_WORKSPACE/wild_gki.fragment"
-          printf '%s\n' 'CONFIG_TRIM_UNUSED_KSYMS=n' >> "$GITHUB_WORKSPACE/wild_gki.fragment"
-        fi
-
         if [ -f "build/build.sh" ]; then
-          GKI_DEFCONFIG_FRAGMENT="$GITHUB_WORKSPACE/wild_gki.fragment" BUILD_CONFIG=common/build.config.gki.aarch64 build/build.sh
-          exit 0
+          SKIP_DEFCONFIG=1 GKI_DEFCONFIG_FRAGMENT="$GITHUB_WORKSPACE/wild_gki.fragment" BUILD_CONFIG=common/build.config.gki.aarch64 build/build.sh
+        else
+          cp "$GITHUB_WORKSPACE/wild_gki.fragment" common/arch/arm64/configs/wild_gki.fragment
+          tools/bazel build --config=release --stamp --defconfig_fragment=//common:arch/arm64/configs/wild_gki.fragment //common:kernel_aarch64_dist
         fi
-
-        cp "$GITHUB_WORKSPACE/wild_gki.fragment" common/arch/arm64/configs/wild_gki.fragment
-        tools/bazel build --config=release --stamp --defconfig_fragment=//common:arch/arm64/configs/wild_gki.fragment //common:kernel_aarch64_dist